Power management in telephony systems remains an important design consideration when power from a common source is shared among multiple subsystems. Minimizing the total peak power significantly reduces system cost and space. Subsystems providing analog telephone FXS (foreign exchange station), BRI (basic rate interface), and DID (direct inward dial) interfaces consume power when applying ringing voltage to telephones and loop power to off-hook telephones, DID trunks and BRI terminal equipment. Ringing telephones generally consumes more power than providing loop power. Intelligent management of ringing in multiport FXS applications reduces cost and space by reducing peak system power consumption.
Certain ports can consume more power than others according to their usage state. FXS ports may consume more power while ringing and, to a lesser degree, when off-hook. BRI ports functioning as NT (network termination) equipment may consume power while supplying loop power to far end TE (terminal equipment) devices. DID ports also consume power while off-hook.